Lead through insulator



Feb- 2, 1954 w. A. voN WALD, JR., ET AL 2,668,187

. LEAD THROUGH INSULATOR 2 Sheets-Sheet 1 Filed June 17, 1949 Imam/tow'WALTER A.VON WALD JR THOMAS E. MARSHALL DI ATTOR N EY Feb. 2, 1954 W.A. VON WALD, JR., ETAL LEAD THROUGH INSULATOR 2 Sheets-Sheet 2 FiledJune 17, 1949 WALTER A. VON WALD JR' THOMAS E. MARSHALL III ATTORN EYPatented Feb. 2, 1954 UNITED STATES ATENT CFFICE Thomas E. Marshall III,Arlington,

Va., as-

signors to Dayton Aircraft Products, Inc., Dayton, Ohio, a corporationof Ohio Application June 17, 1949, Serial No. 99,823

6 Claims.

(Granted under Title 35, U. S. Code (1952),

sec. 266) This invention relates generally to insulated terminals andmore particularly to wire antenna lead through insulators withterminals.

In wire antenna installations such as are required for aircraft service,the antenna lead-in wire must pass through the metal exterior surface ofthe aircraft with sulicient insulation to withstand transmitter voltagesof several thousand volts. Because of slipstream and vibration, aircraftwire antennas are subject to frequent breaku age which necessitatereplacement of the antenna wire. And because lead through insulators maybe and often are located in positions which are not readily accessiblefrom the interior of the aircraft, it is desirable to provide a leadthrough insulator which will. permit replacement of the antenna wirefrom outside the aircraft.

One type of lead through insulator provides a terminal post on both theinside and outside of the aircraft and a new wire may be connectedsimply by attaching it to the outside terminal. However this type cannotbe used with an insulated wire antenna designed to eliminateprecipitation static. Such antennas must maintain 190% insulation up toseveral hundred thousand volts to prevent corona discharge on theantenna. Rather than attempt to maintain said insulation about anexternal binding post it is preferred to run the insulated wire to aterminal inside the aircraft since the corona eliect does not extend tothe interior of the aircraft.

Therefore it is an object of this invention to provide a high voltagelead through insulator having an internal terminal which may be exHternally engaged.

It is another object of this invention to provide a lead throughinsulator for insulated wire antennas having an internal terminal whichmay be externally engaged.

It is another object of this invention to provide a lead through supporthaving a tapered flexibility operative to minimize wire breakage at thelead through insulator.

Other objects and advantages of this invention will be apparent from thefollowing description and accompanying drawings, in which similarcharacters of reference indicate similar parts throughout the severalviews.

Fig. 1 is an exterior perspective View oi a preferred embodiment of thisinvention;

Fig. 2 is a cross sectional view of the embodiment of Fig. 1;

Fig. 3 is a cut away View of a variant embodiment of this invention, and

Fig. l is an enlarged View of a portion of Fig. 2.

Briefly, this invention provides a lead through insulator adapted forflush mounting in an aircraft or other surface and having its externalterminal disposed within the insulator and below the mounting surface.The external terminal is preferably a wire gripping chuck molded intothe insulator whereby the antenna may be connected from outside themounting surface by inserting the lead-in into the jaws of the chuck andmay be disconnected from outside the mounting surface by inserting asmall instrument alongside the wire into the chuck to release the jaws,rIhe insulator may be adapted to receive elbow and ilexible fittings toavoid sharp bends inthe wire and thereby minimize breakage.

Referring now to the drawings in detail, Fig. 1 is a perspective view ofa lead through insulator constructed according to this invention as seenfrom slightly below the ange I0. 'Ihe flange I 6 may be circular and ofabout twice the diameter and molded integral with the insulator body II.A threaded member I2 protrudes from the bottom of insulator body I I andcomprises the internal antenna terminal for connection to any desiredradio equipment. The ange is preferably provided with holes I3 formounting the assembly upon the surface through which the antenna lead isto be passed.

The embodiment shown in Fig. 1 is designed for use with insulatedantenna wire. This wire is typically a 50 circular mil copper weld wireI4 molded in a age diameter polyethelene sheath l5. In Fig. 1 theinsulator II is shown fitted with a lead through support IE which tapersfrom substantially the diameter of the insulator I l to that ofinsulating sheath I5 and preferably has a length 25 or more times thediameter of the insulating sheath I5. The support I6 is preferablymolded of polyethelene, which is a iiexible dielectric that does notbecome stiff even at extremely low temperatures. The conguration oisupport I6 therefore provides a tapering ilexibility which preventssharp bending of wire I4 in the vicinity of insulator II. The taperedilexibility of support I6 is illustrated by dotted lines in Fig. 3.

Fig. 2 is a side elevational view of the embodiment of Fig. 1 showing across section taken along the longitudinal axis. The wire I!! is notshown in cross section. In Fig. 2 the insulator is shown mounted on ametal surface Il such as the aluminum skin of an aircraft. The insulatorshould be mounted with the terminal I2 on the interior of the craft.Surface I'I is provided with a suitable hole large enough to receive theshoulders I8v of insulator I I and a number of smaller holes.correspending to the holes I3 in ange I0 to receive mounting bolts I9.Support I6 has an axial opening 20 large enough to permit insertion ofantenna wire and sheath I4 and I5 but still small enough to provide asnug t. The snug nt over the length of support I6 prevents moisture`from running down antenna wire I5 into the insulator II. The opening 2Umay be more clearly seen in Fig. 3 where the sheath is cut away.

The tapered support I6 has its larger end terminating in a pedestalmember 2l which firmly seats against shoulders I8 of insulator II tofurther prevent sharp bends in wire I4 near its xed termination ininsulator I I. The pedestal member 2l is subtended by a threaded section22A which engages an internally threaded recess 22 in insulator II.

The chuck body 23 has a cylindrical opening 24 at its upper end largeenough to receive sheath I5. As may be more clearly seen in the enlargedview in Fig. 4, opening 24 terminates in the smaller end 25 of thetapered bore 26 machined into chuck body 23. A pair of serrated jaws 2lare inserted in the tapered bore 2G and are pressed toward the small endof the taper by a spring 28. The action of the spring and the taperforces the jaws together. Terminal member I2 has a pair of annulargrooves 29 and 33 at its upper end. The terminal I2 is inserted insidethe chuck body 23 against spring 2B until the upper groove 29 is withinthe chuck. The end of chuck body 23 is then swedged into groove 29 tormly hold the two pieces together. Groove 30 lls with dielectric II whenthe insulator is molded around the chuck rmly holding the chuck with theinsulator.

To install an antenna lead-in, the lead-in is first inserted throughhole 20 in support I6. A short length of sheath I5 is removed exposingbare wire I4. This is inserted into insulator II until the end of wir@I4 has passed between the jaws 21. The lead-in is now securelyconnected, and the lead through support may be screwed into recess 22.Any forces tending to pull the wire I4 from the insulator will cause theserrated jaws 21 to bite into the wire. The jaws will then tend to movewith the wire, and because of the tapered bore 26, the jaws will beforced together and will grip the wire tighter. It has been found thatthe wire will break before the jaws will release the wire.

However, the wire may be very easily disengaged from the chuck fromoutside the aircraft, thus facilitating the replacement of a brokenantenna wire. To disengage the wire, support I6 is removed frominsulator Il and wire I4 is cut off leaving a portion protruding fromthe insulator body. The insulating sheath I5 is easily pulled offleaving only a bare wire. A metal tube 3i having an inner diameter largeenough to accommodate wire I4 is slipped over the protruding end of wireI4 and pushed into the chuck body 23 until it engages jaws 21. Bypushing jaws 21 against spring 28 with tube 3|, the jaws will releasetheir grip on wire I4. Manipulation of the wire retrieving tube 3| maybe facilitated by soldering a handle member 35 to one end thereof.Alternatively, tube 3| may be split longitudinally into two halves,thereby permitting the halves to be placed around the wire instead ofinserting the wire into the tube, thus obviating the necessity forcutting wire I4.

Therefore it will be seen that an insulated wire antenna may beconnected to and disconnected from the lead through insulator fromoutside the 4 aircraft. The only time that a connection need -be madeinside the plane is to terminal I2 when the insulator is installed.

An alternative embodiment is shown in Fig. 3 which is particularlydesirable for installations where the lead-in wire runs considerablyless than degrees from the surface of the plane. In this embodiment anelbow connector 32 is screwed into recess 22 of insulator I I. The elbowhas another recess 33 threaded like recess 22 but disposed at an angleof about ll5 degrees therefrom. Support I6 is screwed into the latterrecess 33 and is accordingly held at an angle of about 45 with thesurface Il. The support is also shown by dashed lines in a bent positionI6' to illustrate the effect of its tapered flexibility in removingsharp bends from the wire at the insulator. By using the elbow insert 32the lead-in may be run parallel to surface I'I without serious straino1' bending of the Wire.

Although certain specific embodiments 0f this invention have been hereindisclosed and described, it is to be understood that they are merelyillustrative of this invention and modifications may, of course, be madewithout departing from the spirit and scope of the invention as definedin the appended claims.

The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

What is claimed is:

1. A lead through insulator and terminal comprising, a dielectric bodymember having a mounting ilange at one end thereof, an insertion typeterminal molded into said body member and having an inner endterminating inside said body member and an outer end protruding from theother end of said body member, the ilange end of said body member havinga recess formed therein to provide access to the inner end of saidterminal, said inner end having a straight-walled recess formed thereincoaxial with the body member recess, at least a portion of the bodymember recess having a transverse dimension equal to that of theterminal inner end recess to provide a straight-walled channelpenetrating said insertion terminal.

2. A lead through insulator and terminal comprising, a dielectric bodymember having a mounting flange at one end thereof, a wire grippingchuck assembly molded into said body member and having its wire grippingend terminating inside said body member and its other end protrudingfrom the other end of said body member, the flange end of said bodymember having a cylindrical recess formed therein to provide access tothe wire gripping end of said chuck assembly, a hollow cylinderintegrally formed in the chuck assembly at the wire gripping end thereofand disposed coaxial with the body member recess, at least a portion ofthe body member recess having an inner diameter equal to that of thehollow cylinder to provide a straight-walled channel penetrating saidchuck assembly.

3. A lead through insulator and terminal comprising, a dielectric bodymember having a mounting flange at one end thereof, a wire grippingchuck assembly molded into said body member and having its wire grippingend terminating inside said body member and its other end protrudingfrom the other end of said body member, the flange end of said bodymember having inner and outer coaxial cylindrical recesses formedtherein to provide access to the wire gripping end of said chuckassembly, said outer cylindrical recess having a larger diameter thansaid inner cylindrical recess, a hollow cylinder integrally formed inthe chuck assembly at the wire gripping end thereof and disposed coaxialwith said body member recesses, said hollow cylinder having an innerdiameter equal to that of said inner body recess to provide astraight-walled channel penetrating said chuck assembly, a flexibletapered member having an axial bore of the same inner diameter as saidhollow cylinder, the larger end of said tapered member having an outerdiameter substantially equal to the inner diameter of said outer bodyrecess and insertable therein.

4. A lead through insulator and terminal comprising, a dielectric bodymember having a mounting ange at one end thereof, a wire gripping chuckassembly molded into said body member and having its Wire gripping endterminating inside said body member and its other end protruding fromthe other end of said body member, the flange end of said body memberhaving a cylindrical inner recess and a threaded outer recess coaxiallyformed therein to provide access to the Wire gripping end of said chuckassembly, a hollow cylinder integrally formed in the chuck assembly atthe wire gripping end thereof and disposed coaxial with said body memberrecesses, the outer body member recess having a larger inner diameterthan said inner body recess, the inner body member recess having aninner diameter equal to that of the hollow cylinder to provide astraight-walled channel penetrating said chuck assembly, a ilexibletapered member having an axial bore of the same inner diameter as thehollow cylinder, the larger end of said tapered member being threaded toengage the threads of said outer body member recess.

5. A lead through insulator and terminal comprising, a dielectric bodymember having a mounting ilange at one end thereof, a wire grippingchuck assembly molded into said body member and having its wire grippingend terminating inside said body member and its other end protrudingfrom the other end of said body member, the ange end of said body memberhaving a cylindrical inner recess and a threaded outer recess formedtherein to provide access to the wire gripping end of said chuckassembly, a hollow cylinder integrally formed in the chuck assembly atthe wire gripping end thereof and disposed coaxial with said body memberrecesses, the outer body member recess having a larger inner diameterthan said inner body recess, the inner body member recess having aninner diameter equal to that of the hollow cylinder to provide astraight-walled channel penetrating said chuck assembly, an elongatedtapered ilexible dielectric member having a base end with a largerdiameter than said outer body recess and tapered to a tip end notsubstantially larger than said inner body recess, a threaded section atthe base end of said tapered member, said tapered member having an axialbore of the same inner diameter as said hollow cylinder, the threadedsection of said tapered member being adapted to t said threaded outerrecess.

6. A lead through insulator and terminal comprising, a dielectric -bodymember having a mounting ilange at one end thereof, a wire grippingchuck assembly molded into said body member and having its wire grippingend terminating inside said body member and its other end protrudingfrom the other end of said body member, the ange end of said body memberhaving a cylindrical inner recess and a threaded outer recess coaxiallyformed therein to provide access to the wire gripping end of said chuckassembly, a hollow cylinder integrally formed in the chuck assembly atthe wire gripping end thereof and disposed coaxial with said body memberrecesses, the outer body member recess having a larger inner diameterthan said inner body recess, the inner body member recess having aninner diameter equal to that of the hollow cylinder to provide astraight-walled channel penetrating said chuck assembly, an elongatedtapered ilexible dielectric member having a base end with a largerdiameter than said outer body recess and tapered to a tip end notsubstantially larger than said inner body recess, a threaded section atthe base end of said tapered member, said tapered member having an axialbore of the same inner diameter as said hollow cylinder, a dielectricelbow-shaped member having a threaded recess at one end identical to theouter body member recess and a threaded section at the other end thereofidentical to the threaded section at the base of said tapered member, aninternal channel connecting the ends of said elbow member and having aninner dimension at least as large as the inner diameter of said hollowcylinder, said elbow member being insertable between the tapered memberand the body member to provide a supported angular entry to said bodymember.

WALTER A. VON WALD, JR. THOMAS E. MARSHALL III.

References Cited in the le of this patent UNITED STATES PATENTS FOREIGNPATENTS Country Date Great Britain Jan. 23, 1934 Number Number

